Telephone recording system



Sept. 15, 1931. H. s. WORRELL TELEPHONE RECORDING SYSTEM Filed July 22.1926 3 Sheets-Sheet INVEJY TOR. 1700mm! J [IQ/we Z A TTORYEY Sept. 15,1931. 5, wo 1,823,717

3' Sheets-Sheet 2 W8 0 U U Q U U mIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII @Tffjiif; 11:11 f I: 1:11:53

73 l I NNNNNN OR p 1931? H. s. WORRELL 1,823,717

TEIQEPHONE RECdRDING SYSTEM Filed July 22, 1926 S'Sheets-Sheet 3 MINVENTOR ATTORNEY Patented Sept. 15, 1931 UNITED STATES PATENT OFFICEHOWARD S. WORRELL, 0F ARDMORE, PENNSYLVANIA, ASSIGNOR TO DICTAPH'ONECORPORATION, OF BRIDGEPORT, CONNECTICUT, A CORPORATION OF NEW YORKTELEPHONE RECORDING SYSTEM Application filed July 22,

This invention relates to amplifying and recording telephonicallytransmitted sounds.

An object of this invention is to provide for. amplifying and recordingsounds transmitted over a. telephonic circuit ataudiofrequencies, andyet avoid detrimental effects to the transmission.

Another object is to provide for controlling the apparatus used toamplify and record sounds, so that it will be practically fool-proof,and will require practically no attention on the part of the user.

A further object is to provide a selfcontained and unitary apparatus foramplifying telephonic sounds and recording such sounds upon a phonographrecord which may be employed subsequently to repeat the sound received.

And a still further object is to provide as a single portable unit anamplifying apparatus utilizing vacuum tubes, a source of plate voltagesupply, a source of filament heating current, and a source of grid bias,if the latter is used, recording and reproducing means, a supply ofphonographic records, and a stand for supporting the above devices.

Other objects and advantages will hereinafter appear.

In the accompanying drawings which illustrate the present invention inthe form at present preferred Figure 1 is a diagrammatic view showingthe parts of the amplifying and controlling apparatus and theirconnections to each other, and the recording mechanism' with itsconnections to the amplifying and controlling apparatus; also theconnections from the telephone line to the amplifying apparatus andrecording mechanism respectively.

Fig. 2 is a side view showing the cabinet for containing the coupling,receiving and amplifying means, and the cabinet for the phonographicrecording means.

Fig. 3 is a perspective view of the device in accordance with thisinvention, showing the supporting stand, etc.

Many proposals have heretofore been made for recording telephonicconversation,

1926. Serial m. 124,2a2..

butthey either failed to comprehend the practical difliculties andproblems, or else made no adequate solution of them. These practicaldifiiculties and problems are for the greater part centered around theconnection or coupling of the commercial telephone lines to thereceiving apparatus of.

the phonographic recording machine.

Commercial telephone systems, including the socalled private systemssuch as are used by railroad companies, contain signalling, monitoringand other apparatus, interference with the functioning of which isdetrimental to the entire system. Such apparatus when operated by directcurrents and controlled by the closing and opening of the telephone lineat the station, usually by the operation of raising the telephone.receiver from its supporting hook, would, of course, be interfered withby an extra connection or circuit which might be tapped across thetelephone lines, and which would permit the flow of direct-currentacross the connection, for this would cause the signalling or otherapparatus to be operated at all times In telephone systems usingmagneto-calling, the problem is somewhat diiferent, for, in that case,magneto or low frequency alternating-currents are used for thesignalling means. In such case the operation of the device would beinter ered with by any connection across the telephone line capable ofpassing an appreciable amount of pulsating toned or straight alternatingmagneto-generated current.

In machine switching telephone systems or automatic telephonesystemsthese terms being used synonymously-the problem is again.different, for in that case the telephone line is closed and the signalsare operated as an incident to accurately timed interruptions in thetelephone line, and in such cases there are, of course, passing throughthe telephone line interrupted or intermittent direct-currents. Hence,any connection across the line which would pass a directcurrent, whichin this automatic system must be interrupted, would render the linetotally inoperative.

Yet, some adequate connection must needs be made to the telephone line,so that the' telephonic signals or conversation may be received andrecorded.

To do this, without deterimentally affecting the telephone line or theapparatus contained therein, the present invention provides a couplingdevice between the tele phone line and the phonographic recordingdevice, which coupling device positively prevents direct-current in thetelephone line from passing through the coupler and yet permits voice orpulsating currents in the telephone line to pass through the coupler,where they are then induced in a receiving circuit, amplified andrecorded on a phonograph.

This connection is also incapable of passing any appreciable amount oflow frequency alternating or magneto current, but, nevertheless, doespermit the high frequency or voice currents to pass through it.

This is done according to the present invention by providing across thetelephone line a coupler which contains :an autotransformer throughwhich the voice currents pass and which induces in the receiving andrecording circuit corresponding.

voice currents of increased E. M. F.; and an isolating condenser inseries with the auto-transformer for permitting the voice currents toflow through the auto-transformer but preventing the direct-currents ofthe telephone line from passing through the auto-transformer,and'preventing lower frequency or magneto-currents from passing throughin any appreciable amount, and also preventing any direct-current in thereceiving circuit from being fed back to the telephone line.

Referring now to the coupling and amplifying system shown in Fig. 1, theapparatus in its preferred form is mounted and supported in a cabinet10, so as to form a complete unit with the exception of. the filamentheating batteries and the plate voltage batteries.

- As shown in Fig. 1, wires 11 tapped from the telephone line 100 areattached to terminals 12 and 13 mounted on the cabinet 10.

. From the terminal 12 a wire 14 leads to an isolating condenser 15,then to a wire 16 connected to an auto-transformer 17 which is connectedby a wire 18 to the terminal 13 for the other wire 11. Thus, a completecir- Connected to the wire 16 of the auto-transformer 17 is a wire 19leading through a switch S, hereinafter described, to a terminal 20connected to the negative side of a filament heating battery 21diagrammatically illustrated in Fig. 1. The Wire 19 is also connected toa wire 22 leading to the filament 23 of a vacuum tube 24, While theother end of the filament 23 is connected by a wire 25 through aresistance 26 to a terminal 27 connected to the positive side ofthefilament heating battery,21. A Wire 28 leads from the upper end ofthe autotransformer to the grid 29 of the vacuum tube 24, the grid beingprovided with a leak 30 and a wire 31 leading to a C or biasing battery32.. whose positive side is connected by a wire 33 to the wire 19leading to the negative side of the filament heating battery.

The voice currents, entering the coupler clrcuit and passing through theauto-transformer 17, induce voice currents of increased voltage in theoutput circuit comprising the auto-transformer 17, Wire 28, grid 29 oftube 24, filament 23, wire 22, wire 19 and wire 16, leading back to theauto-transformer. These voice currents have the same characteristics asthe voice currents in the input circuits and telephone lines except thatthey are of increased E. M. F. The greater portion of these amplifiedvoice currents cannot flow through the said output circuit comprisingthe wire 28 and grid 29, because of the high resistance of the gridcircuit.

The voice currents which pass through the output circuit of theauto-transformer 17, are sufiicient, when picked-up and amplified by thevacuum tube 24 and one stage of audio-frequency amplification which willherelnafter be described, to satisfactorily operate an electricalrecording unit 133 mounted 1n the carraige 134 of a phonograph tooperate upon a record 135 and record therecrll signals received from thetelephone line Hence, for the purpose of picking-up and amplifying theout-put currents of the autotransformer 17, the plate 36 of the vacuumtube 24 is connected to the primary 37 of an audio-frequency transformer38 whose other wire 39 is connected with a terminal 40 which in turn isconnected to the positive side of a plate battery 41 diagrammaticallyindicated in Fig. 1, the negative side of the plate battery beingconnected to a terminal 27 leading back to the filament at the samepoint that the positive side of the filament heating battery isconnected.

-Amplified current flowing through the primary 37 induces current in thesecondary 42 which is connected according to common practice by a wire43 to a grid 44 of a vacuum tube 45 and by a wire 46 with a biasingbattery 32, which is connected by a wire 33 to the negative side of thefilament heating battery 21. The filament 47 of the vacuum tube 45 isconnected to positive and negative wires 25 and 19 respectively by wires48 and 49 respectively, and the plate 50 of the vacuum tube 45 isconnected by a wire 51 to a terminal 52 to which one wire 53 of theelectrical recording unit 133 may be attached, while the other wire 54of the electrical recording unit 133 ma be connected to a terminal 55 onthe ca inet 10. The terminal 55 is connected by a wire 56 to the wire 39leading to the terminal 40 which is connected to the positive side ofthe plate battery.

Accordingly, it will be seen that the voice currents which are inducedin the auto-transformer 17 and which pass through the output circuitconsisting of the wire 28, grid 29, filament 23, and wires 22, 19 and 16are picked-up and amplified by the vacuum tube 24, and further amplifiedby the vacuum tube 45 from which they are impressed upon the wires 53and 54 leading to the electrical recording unit. This is done withoutmaking any direct-current connection to the telephone line 11 andwithout danger of high frequency currents feeding back to the telephone.For, it will be noted, the system does not contain any oscillatingcircuits,

. the auto-transformer 17 and the condenser 15 being in series, and,ofcourse, being so arranged are incapable of setting up oscillation.

In order to facilitate the use of the device, the motor 57 of thephonograph and the filament heating batteries are simultaneouslycontrolled. This is done by connecting the leads 58 and 59 from themotor and its source of supply 60 to terminals 61 and 62 respectively onthe cabinet 10. The terminal 61 is connected by a wire 63 to' a pole 64of a switch S while the knife 65 of the switch S is connected by a wire66 to the terminal 62. The switch S also contains a knife 67 connectedto the wire 19 leading to the filaments of the vacuum tubes, and isadapted to cooperate with the pole 68 connected by a wire-69 to theterminal 20 connected to ,the negative side of the filament heatingbattery 21. The knives 65 and 67 are connected together by an insulatingdenser 15, it is not necessary'or even desirable to provide a switch forbreaking the telephone circuit connections to the device as wasconsidered necessary in some of the early developments of thisinvention.

According to the present invention, a cabinet 10 which contains theapparatus above described, is preferably mounted on a stand 72comprising legs 73 having rollers 74 by means of which the stand may bemoved from place to place as desired. The cabinet 10 is identical withthe cabinet 75 of the phonograph, the top portion of which is hinged at76, the table 77 of the phonograph upon which the carriage 34, record 35are mounted.

According to the present invention, in order that a compact unitarydevice made for receiving, amplifying and recording telephonic signalsmay be provided, the cabinet 75 of the phonograph is mounted directlyabove the cabinet 10 of the receiving and amplifying means as shown inFigs. 2 and 3, and to give free access to the apparatus in the cabinet10, the cabinets 10 and 75 are hinged together at 78 so that the cabinet75 may be swung to position shown in Fig. 2 where it may be supported bya strut 79.

In addition to supporting not only the phonograph but the receiving andamplifying means, the stand 72 is adapted to support containers 80 and81 for the filament heating and plate voltage batteries. Thesecontainers comprise bases 82 secured to the legs 73 and furthersupported by brackets 83 connected to the legs.

The stand 72 is. also adapted to support on a shelf 84 a rack 85 forholding a sufiicient supply of phonographcylinders carried by containers86. As usual, the rack 85 may be rotated to bring a cylinder intoposition where it may be removed. But, in order that the device may bekept as low as possible, sufficient clearance has not been left betweenthe top of the containers 86 and-the stand 72 to permit the removal of arecord and container. Therefore, the supporting shelf for the rack 85 isoffset forwardly so that a portion of the rack projects beyond the frontof the stand 72, and the cylinder and carton which is located in thatposition may be, therefore, readily removed without danger of cominginto contact with the stand.

In practice, wires 11 are connected to wires of the telephone line 100,and also to the terminals 12 and 13 of the coupling, receiving,amplifying and recording device above described. The said device, beingsupplied with the proper batteries, the phonograph motor being suppliedwith a suitable source of current, and a phonograph record being inposition to be recorded, let it be assumed that the telephone bellconnected to the lines put circuit to the auto-transformer.

100 operates or that the station at which the receiving and recordingdevice is located desires to use the telephone, the'person at the 1instrument raises the r ceiver from the hook the calling and calledstations, and both sides of the conversation are, of course, recorded,because the line 100 is the interconnecting line between the twostations and is not merely tapped in at one station.

When the conversation is concluded or the person using the telephone atthe station where the recording device is located desires to have therecording interrupted, the finger-piece 71 is returned to switch-openingposition and the conversation is either continued without recording itor is concluded according to the circumstances.

The opening and closing of the switch S which brings the receiving andrecording mechanism into and out of operation has no effect upon thetelephone line 100, and is not even perceptible.

It should be noted that the input circuit .of the auto-transformer 17,because of the relatively low capacity of the condenser 15 a which inpractice might be 0.25 mid, low

frequency alternating currents or magnetocurrents will not be passedthrough the in- It should also be noted that, because the input circuitof the auto-transformer contains a condenser in series with theauto-transformer, this circuit doesnot interfere with the functioning ofautomatic or machineswitching telephone systems, for there is nopossibility of the circuit being normally closed for the passage ofdirect currents which are used to actuate the switching mechanism insuch systems.

It will, of course, be understood that battery eliminators may be usedin lace of batteries 21, 32 and 41 if desired, an in such cases theeliminators may be supported in the containers 80 and 81 in the samemanner that the batteries 21 and 41 are now mounted. It is merelyimportant that some source of current for heating the filament of thevacuum tube and for supplying voltage for the plate circuits beprovided.

Variations and modificationsmay be madeis claimed as new and for whichit is desired to obtain Letters Patent, is:-

1. An electrical system comprising a commercial telephone line; acoupler connected across said telephone line having in series with it acondenser to permit voice-currents to pass through the coupler butpreventing passage of direct and signal operating currents either to orfrom the telephone line; an output circuit for the coupler; a thermionicdevice in the output circuit; and an electrically operated phonographicrecording device controlled by said thermionic device, said couplerbeing continuously in circuit with the telephone line, and the outputcircuit of said coupler being normally open when the system is not inuse; and means for rendering said thermionic device operative andthereby electrically completing the output circuit of the coupler.

2. A device for receiving and recording telephonic sounds andconversations, and adapted to be tapped across a commercial telephoneline, comprising electrically operated phonographic recording means;thermionic amplifying means for amplifying voice currents to beimpressed upon said recording means; a coupler between said thermionicamplifying means and the telephone line comprising means forming acomplete electrical circuit across the telephone line for the passage ofvoice currents on the input side, and a thermionic device on the outputside connected to the first mentioned thermionic device; control meansfor the phonographic recording means whereby the latter may be renderedoperative to record sound; a source of current for the filaments of thesaid thermionic devices; and means for concurrently operating saidcontrol means to render the phonographic recording means operative andconnecting the thermionic devices to the source of current for thefilaments of thermionic devices, the last-named means being ineffectiveupon the input circuit of said coupler which is at all timeselectrically completed for the passage of voice currents therethrough.

3. The combination in a system for recording telephonic currents ofelectrical phonographic recording means, driving means for saidrecording means, an amplifier connected to said recording means, aconnection between said amplifier and a telephone line, said connectioncomprising a condenser, and a single switch for simultaneously renderingsaid recording means and said amplifier operative and inoperative, saidconnection between said amplifier and said telephone line forming withsaid telephone line a complete circuit through which current flow is notaifected by the operation of said switch.

seesaw merical telephone line; a coupler connected across said telephoneline having in series with it a condenser to permit voice-currents topass through the coupler but preventing passage of direct and signaloperating currents either to or from the telephone line; an outputcircuit for the coupler; a thermionic device in the output circuit; andan coupler.

5/A device for receiving and recording telephonic sounds andconversations, an adapted to be tapped across a commercial telephoneline, comprising electrically operated phonographic recording means;thermionic amphfying means for amplifyin voice-currents to be impressedupon sai recording means; a coupler between said thermionic amplifyingmeans and the telephone line comprising means forming a completeelectrical circuit across the telephone line for. the passage ofvoice-currents on the input side; control means for the phonographicrecording means whereby the latter may be rendered operative to recordsound; a source of current for the filament of the said thermionicdevice; and means for concurrently operating said control means torender the phonographic recording means operative and connecting thethermionic device to the source of current for the filament thereof, thelast named means being ineffective upon the in ut circuit of saidcoupler, which is at a times electrically completed for the passage ofvoice-currents therethrough.

Si ed at Bridgeport, in the county of Fair eld, and State ofConnecticut, this 20th day of July 1926.

HOWARD S. WORRELL.

til

